完全液相法与溶胶-凝胶法制备Cu-Zn-Al双功能催化剂对浆态床一步法合成二甲醚的催化性能比较

摘要

采用完全液相法和溶胶-凝胶法分别制备了组成完全相同的Cu-Zn-Al双功能催化剂,用XRD、氮气吸附-脱附实验和XPS等手段对催化剂的性质进行表征,考察了催化剂对浆态床一步法合成二甲醚反应的催化性能.结果表明,两种方法制备的Cu基催化剂中Cu组分的物相和表面Cu含量明显不同,而催化剂的织构性质基本相同.完全液相法制备的催化剂具有良好的稳定性和较好的选择性,几乎无失活现象;反应后催化剂的比表面积和比孔容均增大,表面Cu含量增加,Cu/Zn摩尔比增大.而溶胶-凝胶法制备的催化剂有明显的失活现象,平均失活率为11.6%/d;反应后催化剂的比表面积和比孔容均减小,表面Cu含量降低,Cu/Zn摩尔比减小,这些可能是导致其失活的主要原因.%The Cu-Zn-Al bifunctional catalysts were prepared by complete liquid-phase(LP) method and solgel(SG) method, respectively. The properties of catalysts were characterized by X-ray diffraction, N2 adsorption-desorption experiment and X-ray photoelectron spectroscopy, and the catalytic performances of dimethyl ether(DME) synthesis directly from syngas in a slurry reactor over LP and SG catalysts were evaluated. The characterization results reveal that the Cu species and surface Cu content in LP and SG catalysts are quite different, but the corresponding texture properties are similar each other. The LP catalyst shows high selectivity and good stability, and its specific surface area, pore volume, surface Cu content and Cu/Zn molar ratio increase after reaction. The SG catalyst shows obvious deactivation, and average deactivation rate is 1.6％/d.The decrease in specific surface area, pore volume, surface Cu content and Cu/Zn molar ratio after reaction is probably the reason of catalyst deactivation.